Friday, May 27, 2011

As mentioned previously, the first thing I started doing was getting DXR to use libclang to build the indexing. As of right now, I have a tool which kind of works. In that it can successfully build a program but utterly fails to produce reliable SQL output due to constantly swallowed segfaults (I think). My test program uses cmake to build, so it "helpfully" hides the noise of what is actually going on, so debugging will have to wait until next week.

The main unexpected hurdle is that for all of the wonderful praise clang has had lavished on it, I have found it surprisingly difficult to use. I had expected to be able to do a more or less straightforward port of dxr.js, with some cosmetic changes to handle differences in naming, etc., between dehydra and libclang. That expectation is now hopelessly gone; libclang provides nothing near the clean API that dehydra does. For example, to get the fully-qualified name of a class, instead of being able to say type.name, I have to walk up the entire AST hierarchy of the class to find all of its containing classes and namespaces to do it myself. If I want to get one for a function (which, in C++, requires differentiating between overloads, so I need type parameters), I have to build my own type-to-string dumper. Indeed, no less than half of my code so far is merely trying to build the type names I need to dump out. In addition, it seems that the clang people are dismissive of an idea to include a higher level API than is currently present.

If you didn't notice from the links, by the way, dxr is now on github.

Monday, May 23, 2011

So, far this summer, I will be mostly putting away Thunderbird work and will instead be focusing my attention on reviving DXR. Sometime this week, I expect to be updating the installation on dxr.mozilla.org (simply so I can match up better on DXR to what I'm doing locally).

What will I be doing on DXR? First and foremost, I will be making it easier to run DXR on anything that is not Mozilla. Or anything that is Mozilla, for that matter. This will be done by cleanly separating the build/instrumentation steps from the rest of DXR. In other words, setting CC/CXX/LD/etc. should be all you need to do build your program.

After that, I will be working on using Clang to get information instead of using gcc+dehydra. If I understand the current Apple development process, supporting clang is essential to supporting Mac OS X builds in the future. I will also work on getting IDL and JS support added.

One other thing I want to do is (time permitting) to get DXR to represent the results of different builds, so that you can get results other than just the current Linux build. I have a list of other ideas to play around with, but I'll leave that for later, since I don't know if I'll time to start them or not.

Don't expect dxr.mozilla.org to see all of the new features immediately. I'll update when I feel like it (i.e., I see enough stability to do it), and it's easier for me to work more locally on my laptop. I also find it easier to do rapid updates on a smaller project than Mozilla which takes quite some time to do clobber rebuilds; I don't know which project(s) I'll be using for all of my work yet, so don't bother asking.